Asthma and COPD Flashcards
Summarize the pathophysiological mechanisms in asthma
Reversible airflow obstruction due to constriction of smooth muscle in the airways
Bronchial wall inflammation leading to mucus hypersecretion and plugging
List common acute asthma precipitants
Viral infection Allergen (dust/pets/pollution/cigarette smoke) Exercise Emotional stress Cold temperature Night time
Define airflow obstruction in the small airways
Airflow obstruction is defined as a FEV1/FVC (measured with spirometry) of <70 %.
What constitutes ‘reversibility’ in bronchodilator response tests for asthma
Post-bronchodilator (10 mins) FEV1 increases more than 200 mL and the increase is greater than 12%.
Classify asthma severity based on % predicted PEFR
Life threatening asthma <33 %
Acute severe asthma 33-50 %
Moderate asthma >50-75 %
Mild asthma >75 %
Define ‘control’ of asthma
No day time symptoms No night time awakening due to asthma No exacerbations No need for rescue treatment No limitations to activity
There may have to be compromise between side effects of treatment and control of symptoms
Describe the step-wise approach to asthma management
Step 1: Salbutamol
Step 2: Salbutamol + Budesonide
Step 3: Salbutamol + Budesonide + Salmeterol (or increased dose of steroid inhaler)
Step 4: As step 3 but trial of high dose inhaled steroid. Consider 4th drug e.g. leukotriene receptor antagonist
Step 5: As step 4 but regular oral steroids at lowest possible dose. Specialist care required
List three different types of inhalers
pressurized meter dose inhaler (pmdi),
breath activated inhalers
dry powder inhalers
How do spacers improve drug delivery
Remove the need for coordination between activation and inhalation
Reduce the velocity of aerosol and subsequent impaction on oropharynx.
What particle size of nebulized solution is appropriate for the treatment of asthma
A drug particle size of 1-5 microns
Should NSAIDS be excluded in all asthmatics
Only 10 % of asthmatics get bronchoconstriction secondary to NSAIDs, therefore it is unnecessary to exclude this useful group of analgesics in all asthmatics.
What are the criteria that define severe asthma
Severe asthma consists of one or more of the following:
Previous near fatal asthma e.g. requiring ventilation
Previous admission for asthma within the previous year
Requires >3 classes of asthma medication
Heavy use of beta-2 agonist
Repeated attendances at A&E
Which commonly used anaesthetic drugs cause histamine release
Morphine (give it slowly
SUX
Thiopental
Mivacurium
Avoid in brittle asthmatics
What is the appearance of the capnograph tracing in asthmatics and why
Up-sloping of the plateau (shark fin like) –> indicates alveoli emptying at different rates.
The expiratory time might need to be prolonged in asthmatics –> what impact does this have on other ventilatory parameters
Decreased inspiratory time –> increased inspiratory pressures
Summarize an approach to laryngospasm, bronchospasm, poor ventilatory effort and pneumothorax
LARYNGOSPASM
Dx - RDS/Stridor/tug/accessory muscles/paradoxical breathing
Rx - Jaw thrust 100% O2 –> CPAP –> Re-intubation
BRONCHOSPASM
Dx - Expiratory wheeze and prolonged expiration
Rx - FiO2 1.0 and BDs
POOR VENTILATORY EFFORT
Dx - Residual sedation/opioids/incomplete recovery from NMB
Rx - BVM with FiO2 1.0 may need re-intubation
(re-sedate in the instance of residual NMB)
PNEUMOTHORAX
Rx - ICD
How is intra-operative bronchospasm diagnosed
Increased airway pressures with difficulty ventilating and upsloping of the capnograph trace ± desaturation
Expiratory wheeze on auscultation
How is intraoperative bronschospasm managed
IMMEDIATE
FiO2 1.0 and call for help
Exclude circuit malfunction/obstruction
Increase [volatile]
High Paw may be needed with I:E 1:4
Consider disconnection to relieve accumulation of autoPEEP
Change LMA to ETT if high pressures required (Aintree fibre-optic).
Drugs:
- B2 agonist puffed into circuit via adaptor or 2.5 - 5 mg salbutamol nebulized into circuit
- If equipment not available: Salbutamol 0.25 mg IV slow IV bolus
SHORT TERM Aminophylline: 5mg/kg IV over 20 mins (If on regular aminophylline: 0.5mg/kg/hr) Hydrocortisone: 100mg IV Magnesium Sulfate: 2 g in 200 ml over 20 mins Adrenalin 10ug boluses IV Ketamine 2mg/kg IV ABG/CXR
DEFINITIVE
If refractory use IV infusion –> ICU